Content for TS 23.479 Word version: 18.0.0
5.11 Open media p. 22
5.11.1 General p. 22
This subclause specifies the open media to start the reception of a given media delivered over an MBMS subchannel.
With this API function, header decompression and FEC decoding can be performed by the MC MBMS user agent or by the MC application.
This API function allows two methods to return the media from the MC MBMS user agent to the MC application: by providing them on a local network interface or by returning them with a callback mechanism.
5.11.2 Procedures p. 22
The procedure specified in Figure 5.11.2-1 allows the consumption of a media delivered over MBMS.
Pre-conditions:
- The MC application is registered towards the MC MBMS user agent
- A MBMS bearer has been announced to the MC application through the MBMS procedures specified in TS 23.280 and registered toward the MC MBMS user agent.
- This MBMS bearer is available within the UE location.
- The MC application has received a MapGroupToBearer message (see TS 23.379, Table 10.10.1.1-1 for MCPTT and TS 23.281, Table 7.10.1.2-1 for MCVideo).
Step 1.
Post-conditions:
The MC application asks to access to the communication with the open media request, by indicating the TMGI of the MBMS bearer and a list of media description information. If the MC application requests FEC decoding and/or header decompression, relevant FEC and ROHC information are included within the open media request; if the MC application wants the media packets to be returned by callback, the MC application provides a callback listener.
Step 2.
The MC MBMS user agent checks if the MBMS bearer of the media is available and starts its reception.
Step 3.
When the media is available, the MC MBMS user agent sends an open media response to the MC application, including a description of the required media (which can be with or without FEC decoding). If packets are returned to the MC application through a local network interface, this network interface name is included in the response.
Step 4.
The MC MBMS user agent makes the media streams available to the MC application according to the configured method for returning media with a help of a local network interface, or by returning the media packets to the callback listener provided in step 1.
- The MC application can consume the required media, until interruption if the MBMS bearer becomes unavailable, or until it closes the media with the close media procedure.
5.11.3 Information flows p. 23
5.11.3.1 Open media request p. 23
Table 5.11.3.1-1 describes the information flow for the open media request.
| Information Element | Status | Description |
|---|---|---|
| TMGI | M | TMGI information of the announced MBMS bearer |
| Media description | O | Describes the multicast IP adresses and ports of the requested media. (e.g. the MBMS subchannel) |
| FEC information | O | FEC information if the MC application requests the MC MBMS user agent to perform the FEC decoding |
| ROHC information | O | ROHC information for the requested media. Indicates if header decompression by the MC MBMS user agent is requested |
| Callback | O | Dedicated callback listener where to return the received media packets. If this IE is not present, the media packets are returned over a local network interface |
5.11.3.2 Open media response p. 24
Table 5.11.3.2-1 describes the information flow for the open media response.
| Information Element | Status | Description |
|---|---|---|
| Media identifier | M | Identifier from the open media request |
| Response code | M | Indicates if the open media request was successful, otherwise an error code |
| Message | O | Additional details |
| Media description | O | Description of opened media, including the multicast IP address and port of the media, after FEC decoding |
| Network interface | O | The local network interface, identified by the name of a network interface card, where the given media can be consumed by the MC application, if packet are forwarded to the MC application over a local network interface according the configured method for media reception |
5.12 Close media p. 24
5.12.1 General p. 24
This subclause specifies the close media invoked by the MC application to stop the reception of a given media.
5.12.2 Procedures p. 24
Step 1.
Post-conditions:
The MC application asks the MC MBMS user agent to stop the reception of media streams with the close media request.
Step 2.
The MC MBMS user agent stops the possible header decompression and FEC decoding.
Step 3.
The MC MBMS user agent notifies the MC application that the media has been closed.
- The closed media streams are no more available to the MC application.
- If no other media from this MBMS bearer are opened, the MC MBMS user agent can end the reception of this MBMS bearer.
5.12.3 Information flows p. 25
5.12.3.1 Close media request p. 25
Table 5.12.3.1-1 describes the information flow for the close media request.
| Information Element | Status | Description |
|---|---|---|
| Media identifier | M | Identifier from the open media request |
5.12.3.2 Close media response p. 25
Table 5.12.3.2-1 describes the information flow for the close media response.
| Information Element | Status | Description |
|---|---|---|
| Media identifier | M | Identifier from the open media request |
| Response code | M | Indicates if the close media request was successful, otherwise an error code |
| Message | O | Additional details |
5.13 Retrieve capability p. 25
5.13.1 General p. 25
This subclause defines API function of retrieve capability.
The retrieve capability request is an API function call and retrieve capability response is returned with a list of capabilities.
The MC application uses this API function call to query what capabilities (e.g. FEC and ROHC) are supported by the MC MBMS user agent.
5.13.2 Procedures p. 26
Figure 5.13.2-1 illustrates the procedure of retrieve capability.
Pre-conditions:
- The MC application has registered towards the MC MBMS user agent.
Step 1.
Post-conditions:
The MC application sends a request to query the capabilities of the MC MBMS user agent.
Step 2.
A retrieve capability response is returned with a list of available capabilities.
- The MC application can further decide whether or not to use these capabilities of the MC MBMS user agent for subsequent communication.
5.13.3 Information flows p. 26
5.13.3.1 Retrieve capability request p. 26
The retrieve capability request does not have input parameters.
5.13.3.2 Retrieve capability response p. 26
Table 5.13.3.2-1 describes the information flow for the retrieve capability response.
| Information Element | Status | Description |
|---|---|---|
| FEC | M | FEC capability of the MC MBMS user agent |
| ROHC | M | ROHC capability of the MC MBMS user agent |
$ Change history p. 27
